How to use the moment of inertia calculator
Estimate moment of inertia for common shapes. Enter mass, radius (or length for rod), shape in the fields above; the moment of inertia is computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- m — Mass (kg)
- r — Radius (or length for rod) (m)
- k — Shape (—)
Worked example
With mass = 5 kg, radius (or length for rod) = 0.4 m, shape = Solid disk or cylinder, the calculator gives moment of inertia ≈ 0.4 kg·m².
Frequently asked questions
What is the formula for the moment of inertia calculation?
Moment of inertia (kg·m²) = k × m × r × r. Here m is mass (kg), r is radius (or length for rod) (m), k is shape (—).
What inputs do I need for the moment of inertia calculator?
You need mass in kg, radius (or length for rod) in m, shape in —. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.